A Sun User’s Guide

Developments in microelectronics over the last 10 to 15 years have led to major changes in the ways people work with computers. More powerful microprocessors and cheaper memory chips have led to personal workstations which have moved computing out of the traditional machine room and into the user’s office. Developments in computer networks have also assisted the redistribution of computing power further into the hands of the users. And the introduction of high resolution displays, with associated pointing devices, has provided new opportunities for improving the interface between user and machine. In the jargon of Information Science, graphical workstations are able to offer more cycles and a greater bandwidth of information communication, between user and machine, than was previously possible.

Many readers will be familiar with the UNIX operating system. Its growth and spread is perhaps one of the most unexpected success stories of computing. Originally implemented on an abandoned PDP-7 minicomputer in 1969 by Ken Thompson, (later joined by Dennis Ritchie), the system is now in widespread use in educational establishments and there are many UNIX look-alikes in the industrial marketplace. SunOS is based on 4.2 BSD UNIX, developed at the University of California, Berkeley, and System V UNIX, developed by AT&T. You may often hear the terms UNIX and SunOS used interchangeably when reference is made to the Sun operating system.

XView is a toolkit of C objects and functions which allow the construction of window-based tools. Tools written using XView comply to the OPEN LOOK interface standard for user interface look-and-feel. The tools introduced in Chapter 1 were written using XView and C. This chapter will consider how tools are written, starting with the tool layout, then handling the interaction between user and tool and finally looking at the internal non-window functions of the tool. The example given will look mainly at the Panel subwindow package. Chapter 4 will look at the Canvas package.

The XView toolkit can used at different levels; the designer chooses which level is appropriate for a given application. At the top level is the Panel package which was described in Chapter 3. This provides a set of powerful objects (panel items) which follow certain conventions and are constrained to the panel style of interface. Panel windows are essentially control windows from which commands are issued and in which control information is displayed. Many applications, however, in addition to control panels, also require an area in which to display more general data — this may be graphical objects, text or a mixture of the two. In the last chapter panel items were not flexible enough for the directory window of our browser. For this type of window, the tool writer has to move down the XView hierarchy (figure 3.2) to a level which provides more basic facilities.

PostScript is a powerful page description language developed by Adobe Systems Incorporated, originally for use on laser printers. It contains a number of powerful graphics and text features useful for desktop publishing and related applications. But it also has many other interesting features.

The Network extensible Window System is a graphical window environment developed by Sun Microsystems. Like its predecessor, SunView, NeWS supports windows, icons, and pop-up menus to provide a more intuitive and productive working environment when compared to character-based terminals.

Administering a Sun Workstation includes such diverse tasks as installing new versions of the operating system, reconfiguring the kernel, installing new application software, creating new user accounts, closing down and restarting the system.

The needs of the Advanced Research Projects Agency (ARPA) community and the desire to access the ARPA Internet network steered the development of sockets on Berkeley UNIX in the network-pioneering days of the early 1980s. At that time, the only standard interprocess-communication facility in UNIX was the pipe, and although it provided a reliable and sequenced flow of data between related processes, it lacked the support for processes on different machines to communicate over networks. Sockets enabled this. Using sockets the machines can exchange messages bidirectionally, they do not have to coexist on the same system and processes do not have to share a common ancestor.

There are several approaches to software development and the one chosen for a particular project will depend on several factors: the size and number of people involved; whether the project is experimental or highly structured; the existing methods adopted by a particular organisation. In general, though, most software development goes through the following cycle: